Since the introduction of saccharin as an artificial sweetener, relative few new sweeteners have been developed. Among those that have been discovered, however, chief among them is the methyl ester of L-.alpha.-Aspartyl-L-phenylalanine, more commonly known as aspartame, disclosed in U.S. Pat. No. 3,492,131 to Schlatter. The viability of aspartame's use in non-dry applications is in serious question, however. Its recent introduction for use in soft drinks in this country was as a mixture with saccharin, the saccharin being used to maintain a sweet taste long after aspartame hydrolyzes to a non-sweet structure.
Thus, a non-toxic artificial sweetener compound comparable in sweetening ability to aspartame but which exhibits superior stability to aspartame in aqueous media would be a useful addition to the artificial sweeteners industry. Such compounds, compositions containing them, and methods of using these compounds as artificial sweeteners are the subject of the present invention.
Japanese Pat. No. 28068 (Takeda) describes aminomalonyl dipeptides which have a C-terminal amino acid of the L-configuration as sweetening compounds for preparing food. Surprisingly, we have found that such is not the case, but rather that the corresponding compounds of the present invention having a C-terminal amino acid of the D-configuration are sweet.